A couple of days ago, as I was finishing the InfoWorld review of Windows 10 Anniversary Update, a good friend (and astute editor) asked me a very simple question: Where is the killer app in Windows 10?

After all, if folks are going to go through the pain and bother of upgrading from Windows 7 or 8.1 to Win10 -- and of climbing the learning curve once again -- there has to be a good reason for the effort, right?

I racked my brain. It's a very pertinent question, especially now that the days of free upgrades are drawing to a close.

Some things in Windows 10 are nice. For example, the ability to run Windows Defender Offline, the rootkit killer, from a Win10 pane is cool. I like the built-in ease of installing a clean copy of Win10 while blasting out manufacturer-installed crap. Having the weather and news appear on Start screen live tiles is nice enough. Setting an alarm with "Hey Cortana" rates as useful. Even allowing Cortana to scan my inbound mail and set appointments -- flight schedules, for example -- comes in handy.

But a killer app?

I combed through all the new features in the Anniversary Update.

The new Start menu looks nice, but it isn't nearly as useful as Windows 7's --all of those apps in a massive, unmanageable blob still makes me cringe.

Windows Ink may be a killer app for some, but I rarely use a stylus and can't draw for beans.

Edge may be a killer app someday, but as it stands right now, it's a fledgling flitting in a field of heavyweights. Chrome and Firefox are still at the head of the list, and will be for quite some time. It doesn't help one bit that changing search engines in Edge requires an act of Congress.

The notification pane (er, Action Center) starts to catch up with where phones have been for many years.

Hello may ring the chimes for some Surface users, but I'm not going to pay for a Surface when a password works just fine.

And the Universal Windows Platform apps? Killers? Gimme a break. Most of them are barely breathing.

What about other apps? Can you think of a Windows app -- just one -- that nails it in Windows 10 but doesn't work well in Windows 7?